The present invention relates to cross-head die apparatus for applying a continuous layer of coating material to a filamentary member as the latter is moved axially through the apparatus. More specifically, the invention relates to an improved core tube for distributing the coating material evenly about the filamentary member.
Applicant's prior U.S. Pat. Nos. 5,031,568, 5,316,583, 5,540,775 and 5,544,403, and application Ser. No. 08,881,576 all disclose cross-head die apparatus including an element known as a core tube which assists in even distribution and axial flow through the apparatus of a flowable coating material which is injected radially into the die body. At least some embodiments of the core tubes of all the aforementioned patents and application include axial grooves through which at least some of the coating material flows from an annular groove in the core tube forwardly toward the die orifice.
In application no. (Model 99B), a pair of axial grooves are positioned at 180 degree intervals and are specified to be optional; when provided, the axial grooves are relatively small with the majority of the coating material flowing through the space between a lip adjoining the annular groove in the core tube and the surrounding portion of the axial bore in the body. No particular number of axial grooves is specified in the referenced patents, although the grooves are of equal dimensions and spaced at equal intervals about the periphery of the core tube. Also, the axial grooves in the referenced patents are described as large in cross section relative to the space between the lip and bore, whereby all or most of the coating material flows through the axial groove.